Repair of CFL
Repair of electronics usually means change of capacitor C3 if he is brobek. When burns fuse, probably will be damaged transistors Q1, Q2 and resistors R1, R2, R3, R5. You can replace fuse with resistor R5. Failures can be multiplied. For example, when is shorted capacitor there can be thermally overloaded transistors and will be destroyed. Best transistors for replacing of original types are MJE13003, but it is not easy to find them. I replaced them with BD129, but they are not available now. There exists other variants like a 2SC2611, 2SC2482, BD128, BD127, but I am not sure if they will be long-life. Original transistors are not available on our market. If doesn't matter size of case TO220, it's possible to use transistors MJE13007.
CFL bulbs basically fail due to breakdown of some very basic electronic components, which are cheap, easily avliable, and easy to test. The components are Electrolytic Capacitors, Transistors, Diodes, Transformer, and Resistors.
The most difficult part of the repair work is to open the enclosure. After the enclosure is taken off it’s found that it has the CFL, Inverter Circuit, and the Housing of the circuit that contains the screwbase.Now the repairing starts with a visual inspection.
If you find any bulged electrolytic capacitor then desolder it out from the circuit and replace it with newer one having same or close capacitance measure, and a voltage rating at least or above 250volts.
Check the transistors. Not by a visual inspection, but by testing them using an ohm-meter. In some cases it might not work due to the base drive circuit. So it’s always recommended to desolder out the transistors, and then test them.
Test the inductor/transformer for open circuit, using an ohm-meter. Check the diodes for forward resistance reading. Make sure that it has no or negligible resistance reading when it is tested reversely. Also check for open circuit.
Have a close look at the resistors. If they appear to be charred, then desolder it out and test it for its resistance reading. In some cases it’s found that resistors open circuit.30% of the failure of CFL bulbs is caused by Open Circuit Resistor that is connected to the mains supply line. It’s basically a low ohm, 0.5 watts resistors.
And if all the above components are found to be ok, then have a continuity test on the Vacuum Tube. If it’s found open circuit then, you cannot do anything further, but can obviously quit the repair work.
